1. Field of the Invention
The invention relates to accurately registering field of views (FOVs) for loosely-coupled modular multi-modality imaging systems, such as cardiac SPECT-CT systems that share the same patient table, but do not have any common installation platform.
2. Description of the Related Art
In modular multi-modality medical imaging systems, wherein modules may be added and combined in a flexible manner, the modules are loosely integrated in that they do not share any common installation platform. In order to make use of multi-modality imaging, the modules must be co-registered with respect to their FOVs so that the images produced by the separate modules can be fused or combined into a composite image for clinical analysis.
In such system, the gantry heights, and thus the centers of rotation of, for example, a single photon emission computed tomography (SPECT) module and a computed tomography (CT) module are individually adjustable, typically within a range of from about −10 mm to about +15 mm. Floor unevenness can also cause a misalignment of ±½ inches between the modules. Additionally, other uncorrelated mechanical and/or installation errors can cause misalignments in heights between the modules. The maximal error in determining a center of reference line for a modular NM imaging system can be over 2 inches. This error is larger than the tolerance of SPECT module on a table height of ±2 mm. Moreover, if the error is not calibrated, the misalignment will result in either a collision in a TOMO scan, or part of the phantom image out of the field of view (FOV). In either case, a FOV calibration procedure fails.
For the foregoing reasons, there is a need for a device and method providing reference height calibration to allow for FOV calibration in a loosely coupled multi-modality modular medical imaging system.